package java_collection.set;

import java.util.Collection;
import java.util.HashSet;
import java.util.Set;

public class HashSetTest {

	public static void main(String[] args) {
		
		Set<Integer> s = new HashSet<>();
		s.add(10); // ok
		s.add(null); // ok
		
		System.out.println(s);

	}

}
